Field and laboratory comparative evaluation of a LAMP assay for the diagnosis of urogenital schistosomiasis in Cubal, Central Angola

OBJECTIVE

To evaluate the performance of Rapid-Heat LAMPellet assay in field conditions for diagnosis of urogenital schistosomiasis in an endemic area in Cubal, Angola, and to assess the reproducibility in a reference laboratory.

METHODS

A total of 172 urine samples from school-age children were tested for microhaematuria, microscopic detection of Schistosoma haematobium eggs and LAMP for DNA detection. Urine samples were stored in a basic equipped laboratory. Field-LAMP tests were performed with and without prior DNA extraction from urine samples, and the results were read by turbidity and by colour change. When field procedures were finished, samples were sent to a reference laboratory to be reanalysed by LAMP.

RESULTS

A total of 83 of 172 (48.3%) were positive for microhaematuria, 87/172 (50.6%) were microscopy-positive for S. haematobium eggs detection, and 127/172 (73.8%) showed LAMP-positive results for detecting S. haematobium using purified DNA and 109/172 (63.4%) without prior DNA extraction. MacNemar's test showed a statistical significant relation between LAMP results and microscopy-detected S. haematobium infections and microhaematuria (P < 0.001 in both cases), respectively. When samples of purified DNA were reanalysed in a reference laboratory in Spain using the same LAMP methodology, the overall reproducibility achieved 72.1%.

CONCLUSIONS

The ease of use, simplicity and feasibility demonstrated by LAMP assay in field conditions together with the acceptable level of reproducibility achieved in a reference laboratory support the use of LAMP assay as an effective test for molecular diagnosis of urogenital schistosomiasis in endemic remote areas.

Microhaematuria as a diagnostic marker of Schistosoma haematobium in an outpatient clinical setting: results from a cross-sectional study in rural Ghana

The utility of microhaematuria (as measured by urine reagent strips) as a surrogate marker for Schistosoma haematobium infection is not established in patients with urogenital symptoms presenting to clinical settings, although previous studies have demonstrated its utility in screening asymptomatic individuals in large community or school-based settings. In this cross-sectional study of 201 patients, multivariate analysis demonstrated microhaematuria as an independent predictor of S. haematobium infection (OR, 4.29; 95% CI, 1.6-11.9) in individuals presenting with urogenital symptoms to an outpatient medical department (OPD) at a rural Ghanaian medical center. Microhaematuria is predictive of S. haematobium infections in clinical settings in endemic regions.